Overall Objectives of Project: 1) To determine the role of iron and pathogenesis of fibrosis in hemochromatosis. 2) To study metabolic abnormalities of iron deficient red cells with specific reference to the maintenance of the integrity and plasticity of red cell membrane. 3) To characterize the membrane receptor sites for transferrin and to determine their role in regulation of intestinal absorption of iron in its subsequent delivery to erythroid cells. Goals for the Current Year: 1) To verify the increased deposition of collagen in response to experimental iron overload in animals in whom proline hydroxylase activity has been demonstrated to be increased. 2) To establish a model in which selenium balance can be studied in various stages of iron repletion. 3) To characterize membrane abnormalities in the iron deficient state.